1. Field of the Invention
The present invention relates to an ink jet recording head for discharging a liquid from an orifice to form a droplet and a method for manufacturing the same.
2. Related Background Art
As for this type of an ink jet recording head for discharging a liquid from an orifice to form a droplet, an ink jet recording method disclosed in, for example, Japanese Patent Application Laid-Open No. 54-51837 has a different feature from the others in exerting thermal energy on the liquid to thereby obtain motive power for discharging the droplet.
That is, the recording method disclosed in this publication features that a liquid is heated when it receives an action of thermal energy to thereby produce a bubble, which in turn causes a droplet to be discharged from an orifice at the tip of a recording head section, which droplet then sticks to a recording medium to record information.
A recording head applied to this recording method typically comprises a liquid discharge section which includes as components an orifice from which a liquid is discharged and a thermal acting portion section which has a liquid channel to communicate with the orifice and at which thermal energy acts on the liquid to discharge a droplet, an exothermic resistor layer serving as a thermal converter, which is means for generating thermal energy, an overlying protection layer for protecting this exothermic resistor layer from ink, and an underlying layer for accumulating heat.
To improve a printing speed of such an ink jet recording head that obtains motive power for liquid discharge by exerting thermal energy on a liquid, its frequency response may be improved to solve the problem in performance. To improve the frequency response, it is necessary to improve ink refilling performance after droplet discharge. To improve the ink refilling performance, it is in turn necessary to reduce flow resistance over a passage from an ink inlet to an ink orifice.
If the flow resistance is reduced, however, a bubbling pressure escapes toward the ink inlet to result in a drop in discharge speed and so worsen stability, thus deteriorating the discharge performance hence printing. Accordingly, it has been difficult to improve the frequency response while maintaining the discharge performance at a proper level.
Furthermore, to meet a recent market desire for a higher image quality and so to achieve high-resolution printing by use of a small droplet, an ink jet print head needs to be arrayed to provide a high density and also to fly a minute droplet from an orifice.
On the other hand, there has been made such a proposal for providing a movable member, which provides a so-called fluid diode, somewhere in a nozzle channel between the ink inlet and the orifice to thereby improve the frequency response while maintaining proper discharge performance. Such a conventional ink jet recording head, however, may sometimes be subject to flake-off or destruction of the movable member.
In view of the above, it is an object of the present invention to provide a high-density, high-accuracy, and highly reliable ink jet recording head which solves the above-mentioned problems to thereby enable forming a movable member in the nozzle channel between the ink inlet and the orifice, thus improving the frequency response while keeping proper discharge performance.
To this end, a method of the present invention for manufacturing an ink jet recording head having, on a substrate provided with an exothermic resistor, an ink orifice provided in correspondence to said exothermic resistor and a nozzle channel communicating with said ink orifice, with a movable member formed in said nozzle channel somewhere between said exothermic resistor and an ink inlet for supplying ink into said nozzle channel in such a configuration that a bubble generated in the ink in the nozzle channel by heat generated by said exothermic resistor is utilized to discharge the ink from said ink orifice, comprising the step of:
preparing the substrate provided with said exothermic resistor;
applying such first resin on said substrate as to provide a first mold shape for forming said nozzle channel and said movable member;
forming said first mold shape using said first resin;
applying on said substrate second resin over said first mold shape for forming said nozzle channel and said movable member; and
removing said first mold shape.
By this manufacturing method, the movable member can be molded at the same time as the nozzle mold shape and so can be formed together with the nozzle channel by photolithography at a high density and high accuracy, thus manufacturing a high density, high accuracy ink jet recording head.
Furthermore, to form the movable member, a mask pattern having a width less than a resolution limit of said first resin can be used to form such a portion of said first mold shape as to be used to form said movable member and use the resin applied on the portion later, thus forming the mold shapes of the nozzle channel and the movable member forming portion using the same mask. Accordingly, the nozzle channel and the movable member can be formed at a mask formation accuracy. Furthermore, it is possible to eliminate one patterning step, thus reducing the costs.
Another ink jet recording head of the present invention for utilizing a bubble generated in ink in a nozzle channel when the ink is heated by an exothermic resistor, to discharge the ink from an ink orifice, comprising:
a substrate provided with said exothermic resistor; and
said nozzle channel formed on said substrate, with a movable member formed in said nozzle channel somewhere between said exothermic resistor and an ink inlet for supplying the ink into said nozzle orifice, said movable member having a supporting point thereof on such a wall of said nozzle channel as to be opposed to said substrate and a free end thereof on a surface of said nozzle channel on the side of said substrate and being formed integrally with said wall opposed to said substrate.
In this ink jet recording head, the same material can be used to form the ink channel and the movable member and integrally, so that it is possible to make this ink jet recording head highly reliable and this movable member difficult to flake off or destroy.